And it’s growing. A gory video taken by a visitor at the Yancheng Safari Park has now raised concerns about the safety of animals at that particular Shanghai zoo and the well-being of creatures at all Chinese facilities.

The video shows a group of men in raincoats pushing a donkey down a wooden ramp and into a moat, where two tigers attack it. The donkey thrashes around underwater. Though the video is only about a minute long, one Chinese newspaper reports it took 30 full minutes for the animal to die.

“It’s a terribly sad video because everything in it is suffering, whether it’s the donkey, whether it’s the tigers, whether it’s the public watching them,” Doug Cress, the chief executive officer at the World Association of Zoos and Aquariums, told National Geographic.

The incident is seen as harmful to the tigers because — being raised in captivity — they clearly don’t know how to prey on such a large animal.

If you watch, it’s a very different sort of attack than that you see of these cats in the wild. It’s a comparably messy and long-lasting approach that put the predator at risk of injury as well as the prey.

The incident occurred when angry zoo shareholders (who were upset by the lack of returns from their investments) hired a group of men to capture some of the zoo’s animals (including the donkey) and sell them to people outside.

But when the men were stopped by zoo security at the gates, they had to come up with a plan B.

They’d shove the donkey into the tiger enclosure, they decided. That way, shareholders would at least “save on animal feed,” one investor told the Guardian.

The shareholders released a statement saying that the feeding was a form of protest against a court freezing the zoo’s assets.

“Shareholders are very unhappy about this,” the statement reads. “So in a rage, a live donkey and sheep will be fed to the tigers.”

The statement also argued that the court’s decision has caused animals harm — saying that two giraffes have died since the assets were frozen.

For many, this explanation doesn’t do much to ease concerns.

“If the zoo had the proper barriers between humans and the enclosures, first you couldn’t have gotten the animals out of the enclosure,” Cress said. “And second, you couldn’t have tossed them into the tiger enclosure. Clearly, the barrier and safeguards aren’t effective at that zoo.”

Though the zoo business has been booming in China over the past 20 years, serious animal welfare concerns continue to pop up.

Zoo visitors have been known to throw rocks and garbage at the animals and — at Yancheng in particular — they’re allowed to purchase live ducks and chickens to throw into lion and tiger cages.

Other parks let guests buy live sheep, goats, pigs, and cows to feed to the big cats.

“If someone pays enough money, some parks are willing to do anything,” Dave Neale, the animal welfare director of Animals Asia, told National Geographic. “It undermines the educational value of a zoo — I don’t see the educational value to something like that.”